1. Field of the Invention
This invention relates to telecommunications. More specifically, it relates to a method of informing a home network operator about locations of their subscribers while the subscribers are roaming on visited networks.
2. Brief Description of the Related Art
Home mobile network operators have a strong need to know where their subscribers are roaming at any instant in time. This knowledge of the location of each out-bound roaming subscriber is imperative for a number of fundamental operations including tracking, billing, and provision of value added services. Many home networks bill their subscribers for out-bound roaming services using different rates for different countries, and, in some cases, billing rates can vary even within a single country based on the out-bound roamer's location. Without having accurate and current information regarding the locations of the out-bound roaming subscribers, home networks may not be able to bill those subscribers properly.
An effective method of providing a roaming subscriber's information to home network is by using Informational Elements (IEs) of the GTP-C v1 protocol for GSM networks or IEs of the GTP-C v2 protocol for LTE networks. Specifically, Routing Area Identity (RAI) and User Location Information (ULI) IEs can be used to convey the out-bound roamer's location to the home network. The visited network's Serving GPRS Support Node (SGSN) is responsible for populating RAI and ULI IEs. However, because per GSM GTP-C v1 protocol, RAI and ULI IEs are optional, not all SGSNs populate these IEs. When RAI IE, ULI IE, or both are not present in a Create PDP Context Request message or an Update PDP Context Request message, the home network may be unable to identify the roamer's current location.
Accordingly, what is needed is a method of providing information regarding its out-bound roamers' location information to the home network in a consistent and reliable manner. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the field of this invention how this objective could be achieved.